The present invention relates to a switch used in an automated transport system for moving a rail section between positions in line with a main rail or in alignment with an individual or paired subsidiary loops disposed adjacent the main rail, and more particularly relates to an improvement in such an apparatus wherein means are provided for producing it less expensively and for moving the rail section which it carries between its selective positions with enhanced smoothness.
In automated transport systems of the type which this invention is concerned, trolleys carrying work pieces are shuttled between a main rail and subsidiary loops positioned in pairs along the main rail. Such a system is disclosed in U.S. Pat. No. 4,615,273 issued on Oct. 7, 1986 to Osthus et al. and being commonly assigned with the assignee of the present invention. In this patent, a three position transfer sWitch is disclosed for moving a transfer rail between a gap formed in the main rail and the entrance ends of each juxtaposed subsidiary loop positioned on opposite sides of the main rail. However, switches such as these have been found to be quite costly to manufacture. One factor contributing to this cost is the size of the switch frame needed to house the actuator used for powered movement of the transfer rail section. Hitherto, the actuators employed in these switches were elongate units comprised of two actuator assemblies connected end-to-end with one another, which arrangement being considered necessary to achieve movement of the transfer rail between its discrete positions. Also, in these prior art switches, the bracket connecting the transfer rail with the switch was received for movement within guide slots formed in the switch frame, the formation of which slots likeWise added to the manufacturing cost of the switch. Furthermore, the material from which these guide slots could be formed was limited to that material used in the formation of the switch frame. This often resulted in a significant amount of friction being produced by the bracket as it slid within the guide slots in turn causing greater actuator wear thus shortening the useful life of the switch.
Accordingly, it is a principal object of the present invention to provide a switch of compact design for selectively moving a transfer rail section between a plurality of discrete positions in a conveyorized transport system such that its compact size enables smoother and more quiet moving of the transfer rail section between its discrete positions.
The invention further aims to provide a switch of the foregoing character having separately formed guides upon which guides a bracket carrying the transfer rail section is slidably supported.
Another object of the present invention is to provide a switch smoothly moving a bracket carrying a transfer rail section between discrete positions by supporting it for movement on separate guide rods upon which low friction bearings interposed between the guide rods and the bracket bear.
Yet still another object of the present invention is to provide a switch of the foregoing character employing a plurality of actuators slidably mounted for unitary movement on individual guide rods such that the actuators are capable of sliding with the bracket carrying the transfer rail thereby effecting an overall efficiency of movement within the switch.
It is yet another object of the present invention to provide a double acting switch having means for transferring a trolley to an entrance end of a subsidiary loop and for receiving a trolley from an exit point in the subsidiary loop, with the entrance being downstream of the exit point relative to the general direction of trolley movement so that subsidiary loops can be located directly across from one another on a main rail in pairs and a trolley can be transported between subsidiary loops of a given pair or can be recirculated within a single subsidiary loop as desired.
Further objects and advantages of the invention will be apparent from the following description and drawings and from the appended claims.